linux-kernel - Re: [PATCH] iio: adc: fsl-imx25-gcq: fix the right check and simplify code

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Date:   Sat, 31 Jul 2021 17:45:51 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Tang Bin <tangbin@...s.chinamobile.com>
Cc:     knaack.h@....de, lars@...afoo.de, shawnguo@...nel.org,
        s.hauer@...gutronix.de, festevam@...il.com,
        linux-iio@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Zhang Shengju <zhangshengju@...s.chinamobile.com>
Subject: Re: [PATCH] iio: adc: fsl-imx25-gcq: fix the right check and
 simplify code

On Tue, 27 Jul 2021 20:52:09 +0800
Tang Bin <tangbin@...s.chinamobile.com> wrote:

> For the function of platform_get_irq(), the example in platform.c is
> *		int irq = platform_get_irq(pdev, 0);
> *		if (irq < 0)
> *			return irq;
> So the return value of zero is unnecessary to check. And move it
> up to a little bit can simplify the code jump.
> 
> Co-developed-by: Zhang Shengju <zhangshengju@...s.chinamobile.com>
> Signed-off-by: Zhang Shengju <zhangshengju@...s.chinamobile.com>
> Signed-off-by: Tang Bin <tangbin@...s.chinamobile.com>

Hi,

Logically it is better to keep the irq handling all together, so 
I would prefer we didn't move it.

Also, platform_get_irq() is documented as never returning 0, so the current
code is not incorrect.  As such, this looks like noise unless there is
some plan to make use of the 0 return value?  What benefit do we get from
this change?

Thanks,

Jonathan

> ---
>  drivers/iio/adc/fsl-imx25-gcq.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iio/adc/fsl-imx25-gcq.c b/drivers/iio/adc/fsl-imx25-gcq.c
> index 8cb51cf7a..d28976f21 100644
> --- a/drivers/iio/adc/fsl-imx25-gcq.c
> +++ b/drivers/iio/adc/fsl-imx25-gcq.c
> @@ -320,6 +320,10 @@ static int mx25_gcq_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	priv->irq = platform_get_irq(pdev, 0);
> +	if (priv->irq < 0)
> +		return priv->irq;
> +
>  	for (i = 0; i != 4; ++i) {
>  		if (!priv->vref[i])
>  			continue;
> @@ -336,14 +340,6 @@ static int mx25_gcq_probe(struct platform_device *pdev)
>  		goto err_vref_disable;
>  	}
>  
> -	priv->irq = platform_get_irq(pdev, 0);
> -	if (priv->irq <= 0) {
> -		ret = priv->irq;
> -		if (!ret)
> -			ret = -ENXIO;
> -		goto err_clk_unprepare;
> -	}
> -
>  	ret = request_irq(priv->irq, mx25_gcq_irq, 0, pdev->name, priv);
>  	if (ret) {
>  		dev_err(dev, "Failed requesting IRQ\n");